Defensive venoms secreted by skin glands (principally the parotid glands) of the toad owe their high toxicity to bufadienolides that occur both free (bufogenins) and combined (bufotoxins). These compounds have digitalis-like properties and have been used medicinally in a traditional Chinese preparation, Chan Su. The best characterized is bufotoxin (24), from the European toad Bufo vulgaris and the Asian toad Bufo gargarizans, the bufogenin of which is bufotalin, a close structural relative of gitoxin. Sapogenins are steroids of the spirostan type that occur widely and in great variety in plants. They are linked to sugars as glycosides, usually through a ...(100 of 7003 words)